Reciprocating bender with sliding side shapers



Nov. 14, 1950 E. .1. BOHABOY RECIPROCATING BENDER WITH SLIDING SIDE SHAPERS Filed July 20, 1945 4 Sheets-Sheet 1 5: 4 Z. A ff A Tram 5r Nov. 14, 1950 E. J. BOHABOY ,5

RECIPROCATING BENDER WITH SLIDING SIDE SHAPERS Filed July 20, 1945 4 Sheets-Sheet 2 ATTORNEY Nov. 14, 1950 E. J. BOHABOY 2,530,222

' RECIPROCATING BENDER WITH SLIDING SIDE SHAPERS Filed July 20, 1945 4 sheets-sheet s as 'H ATTORNEY Nov. 14, 1950 E. J. BOHABOY 2,530,222

RECIPROCATING BENDER WITH SLIDING SIDE SHAPERS Filed July 20, 1945 4 Sheets-Sheet 4 A TTOR/VEY Patented Nov. 14, 1950 UNITED. sures PATENT OFFICE.

REcIPRocAT'ING 'ENDER Wi'lfi SLI'Di'NG SIDE SHAPERS Edward .r. B abay, Berwyn; 111., assignor to Western Electric Company, Incorporated, New York; N. Y., a corporation of New York Application July 20', 1945, Seria1N 606,218

An object of this invention is to provide an" efiicient and effective forming apparatus for forming loop-shaped articles.

In accordance with one embodiment ofthe invention, there is provided a punch press operated apparatus in whicha re'cipro ca'table mandrelis disposed in spaced relation" to a group "of three dies comprising a middle longitudinally movable die and apair of transversely movable dies each having a forming edge adapted to cooperate with the mandrel in forming a straight blank o'f'material; which is positioned between the mandrel and the: dies, into a loop-shaped article. The longitudinally movable middledie, disposed in alignment With'the mandrel, is yieldin'gly held in its' fo'rward position between the pair of transversely ovanerbrmm dies and acts to form the blank into u shape when the mandrel is moved against the die after which is moved out of the way-of the other forming d'ies;

tionedin alignment therewith, and the trans" versely" movable forming dies actuated to plete the operation of forming the article about the'mandrelw The invention will be more fully understood from the following 'd'escription'taken in connec tion with the accompanying drawings} in whiclri- Fig. l is a plan view-cf the apparatus "showing the actuating cams in section thereon; 7

Fig. 2 is a'detail pla'n view of one of the trans-' versely movable forming'die's;

Fig. 3 is a vertical transverse sectional-view taken on the line 3-3 of Fig. If g Fig. 4 is a fragmentary transverse vertical sectional view taken on the line i lof'Figf. 1;

Fig. 5 is a plan view of a portion of the appa-' ratus with some of the parts removed showingfthe mandrel and the forming dies in their normalpo sition and showing ablank in'position therebe' tween in dotted linesj V Fig. 6 is a fragmentary plan view of the apparatus similar to Fig. 5'showing the mandrel in its advanced position after it has formed the'blankf into U-shape and moved it to aposition infaligriment with the I transversely movablediesand showing. in dotted lines the'forming position of" the. transversely movable dies;

Fig"; '71s a fragmentary'vertical'sectional View through the'rnandrel taken on-theline" ll of and the mandrel andU-formed blank arelpo'si Fig. 8 is a view of the completed article as formed by the apparatus and showing in dot and dash' lines the blank before being formed by the apparatus; I

Fig. 9 is' a central vertical longitudinal sectional View taken on the'line 9 of Fig. 1

Fig. 10 is a fragmentary vertical longitudinal sectional View taken on the line ill-! 6 of Fig. 1; and

Fig. 11 is a' bottom' view of the mandrel and theslide on which it is mounted.

In the embodiment of the invention illustrated in the accompanying drawings, the apparatusoperates to form a flat blank or strip of 'material lti into a loop-shaped article lfivha-ving end;

portions ii and i8 extending radially outwardly therefrom (Fig.8). The apparatus for forming the article is adapted" to be used in a'punc'hpress having a relatively short stroke. shown particularly in Figs. 3 and 9, the apparatus comprisesa die holder or block 20 secured to the bolster plate 2! of a punch press. and has fixed to the topside thereof in any suitable manner a slide supporting plate 22. A mandrel slide 25', niounted for longitudinal reciprocation a slideway 25 of the slide supporting plate 22, is apertured at 21 to receive shanl; 28 of a cylindrical portion 29 oi a mandreltil which-is retainedthei in by a' lock screw 3i, theen'd Ofwhichengagesf a recess 32 in-the'shank 28 thereof (Fig; 9). A

thin blade-like member 35, engaging the cylindrical portion of the mandrel and forming'j an extension thereof about which the blank l5is formed; is enlarged at 36 (Fig. ll) and adjustably' mounted'on the underneath side of the mandrel slide 25. The member 35 is retained in adjusted" position by a machinescrew 3! passing through a slot 38 in the slide and engaging a threaded" aperture 39 in the enlarged portion 36 of' the" member 35; A plate 42, secured to the top of the supporting plate 22; overlies'and retains the"- slide 25 inits Way 26.

mandrel the proper distancein timed relation with the other mechanism later'to be (resented;

The cam member 3 5 is attached to a'headior punch plate M which is secured-t0 and'is reciprocatable with a'ram 148 of the punch press-.-

-Spaced'from and in alignment with the manner 3|] andreciprocally mounted in a-way fiiinthe' plate 22 is a slide 50, the forward end of which has secured thereto a replaceable die 52. The die 52 is provided with a semi-circular recess 53 adapted to receive a portion of the cylindrical part 29 of the mandrel 39 therein, the parts being proportioned to provide suificient clearance to receive a blank I therebetween.

The replaceable die 52 is provided with a dovetailed end which engages in a dove-tailed slot in the slide 59 and rests on the bottom of the way tally disposed pin 51 slidably mounted therein which is provided with an enlarged head 58, slidable within an aperture 59 in the slide 59. The front end of the pin 5'! terminates in alignment with the front end portions of the die 52 (Fig. 5) and is adapted to cooperate with th mandrel 29 to engage and grip a blank I5 during the forming operation as will hereinafter be described. The pin 57 is urged in a forward direction by a spring 69, which seats in a recess BI in a cylindrical block 92 engaging the end of and movable with the slide 59. The die 52 and the slide 59 are urged forward by a helical compression spring 64, one end of which engages the cylindrical block 62 and the other end of which engages the closed end of a tubular housing 65. The housing 65 is secured to a block 66 which is fixed to the die block 29. The die 52 is stopped in its forward position by the engagement of its forward end portions with a shoulder 68 formed in the slide supporting plate 22 at the forward end of the way 5L The slide 59 and die 52 are retained in the way 5i by a pair of plates 98 and 69 which are suitably secured to the plate 22 and which overlie a portion of the slide and die, as shown in Figs. 1 and 4.

A pair of transversely movable forming dies '12 and 73 (Figs. 1 and 3) are mounted for reciprocation in ways I4 and I5 of the slide supporting plate 22 and are disposed on opposite sides of and adjacent the front end of the die 52. The inner ends of the dies '12 and I3 are provided with curved forming portions 18 and I9, and with fiat portions 89 and 8I, respectively, which conform to and cooperate with the cylindrical portion 29 and th fiat portion 35 of the mandrel to form a portion of the article l6. The dies I2 and I3 are provided with cam slots 84 and 85 for receiving cam members 89 and 8'! for imparting reciprocative movement thereto. and 81 are attached to the head 4'! and are shaped to impart the desired movement to the dies 12 and I3 and in timed relation to the movement of the mandrel 29. The plates 68 and 69 overlie the dies 12 and 13 to retain them in their respective ways. Clearance holes are provided in the die block 29, the supporting plate 22, and the retaining plates 42, 68 and 69 for the reciprocation of the cam members 45, 8B and 81.

The blank I5, in the form of a narrow straight strip of thin fiat material having a predetermined length, is positioned between the dies and the mandrel adjacent the end portions of the die 52 and portions of one side of the dies I2 and I3, as indicated in Fig. 5. To support the blank l5 in horizontal alignment with the mandrel and the dies, the plate 22 is shaped to provide supporting surface 99 which extends forward from the dies to accommodate the movement of the blank as the blank is formed about th mandrel. The blank I5 is positioned longitudinally on the supporting surface 99 by a pair of end gages 9| and 92 which are adjustably mounted in ways 93 and 94 in the plate 22. The gages 9| and 92 are held in ad justed position by the retaining plates 96 and 91,

The die 52 is apertured to carry a horizon- The cam members 86 4 each engaging one of a series of notches 98 and 99, of the gage members 9I and 92, respectively. Shallow vertical notches I99 and I9! for receiving the ends of the blank I5 are provided in the ends of the gage members 9| and 92 and act to support the blank I5 in the vertical position on the supporting surface 99 in cooperation with some of the vertical surfaces of the dies 52, I2 and I3.

Portions of the front edges of plates 68 and 69 and the rear edge of the slide 25 and a portion of the rear edge of the plate 42 are positioned so as to form a vertical slot or passageway I99 (see Fig. 10) in alignment with the notches I99 and [M of the gagermembers BI and 92 to guide a blank I5 into the loaded position illustrated in dotted lines in Figs. 5 and 9.

To aid in feeding a blank l5, a feeding mechanism is provided and comprises a pair of transversely adjustable guide members I 95 and I96 having ledges or rails I91 and I98, on which the blank I5 may be supported. Vertical shoulders I99 and H9, extending upwardly from the rails I91 and I 98, respectively, are formed on the guide members I95 and I96 to engage the ends of and guide the blank I5 during its forward movement. The forward ends of the rails I91 and I98 and a portion of the plates 58 and 69 are bevelled, as indicated at II2 (Figs. 9 and 19), to form an inclined surface to facilitate the movement of the blank into the vertical pasageway I94 and to the loaded position. A reciprocatable feed plate H5, having an upwardly extending handle II 6 and resting upon the rails I91 and I98, is adapted to engage and feed a blank I5. To prevent the feeding of more than one blank at a time, gage blocks H8 and H9 are mounted on the shoulder portions I99 and H9 of the guides I95 and I 96 and are spaced from the top surface of the rails I91 and I99 a distance sufficient to permit only one blank to pass therebetween.

The guide members I95 and I96, in order to accommodate blanks of various lengths are adjustably mounted in ways I22 and I23 in the plates 68 and 69, respectively, and are secured in position thereon by machine screws I24 and I25, which pass through slots I26 and I 2'! in the guide members I95 and I96, and engage threaded apertures in the plates 68 and 69, respectively. The guide member I96 is adjustable to a number of predetermined positions and for this purpose it is provided with a plurality of equall spaced apertures I28 arranged in a row, each one of which may be aligned with an aperture I29 in the plate 69 to obtain one of the predetermined positions. The guide member I96 may be held in the selected position by a pin I39 inserted through the aligned aperture I28 of the guide member I96 and into the aperture I29 of the plate 69. One end of a blank I5 may be then positioned on the ledge I98 and engage the shoulder tightening the machine screws I24 and I25.

The apparatus is designed to operate on blanks of various predetermined lengths and form them into completed articles of various sizes. For this purpose, removable mandrels and dies of various sizes are provided and used as needed.

In the operation of the apparatus, a blank I5 is placed on the guide rails I91 and I98 and fed forward thereon by the actuation of a feed plate I I 5. The blank slides down the inclined surface 3. H2 and through. the vertical slot: H14 and comes to rest on the supporting surface 90: in the position indicated in. Figsp5 and 9 with its ends engaging in the notches. H10 and till of. the gage members 9! and 92,- respectively. The ram 48 is then actuated to: reciprocate the head 41 and the cams d5, 85. and B'ii, attached thereto. On the first portionv or". downward movement of the came 45, the slide and the mandrel Silwill be moved toward the die: 52 during which movement the mandrel will. engage the blank [5- intermediateits. ends. and move it into the recess 53v on the die 52 and form itinto U-shape. The pin 5'5. will press. the blank against the mandrel and prevent its. being displaced during the form ing operation. The. die. 52 is maintained in a stationary condition in its. forward position by the action oi thespring 6 k While the blank i5 isbeing formed" into Llg-shape. After the blank is formed. into Usshape, the mandrel imparts. a. rearward movement to the die 52 and the slide, 5.! against. theaction of the spring 64. until the parts. have reached the position shown in Fig. 6, at which. time the die 52 will have been moved out of'the path. of "travel of the trans versely movable forming diesiz and i3 and the mandrel 29 and the U- haped blank thereon will have beenpositioned inv alignment with the forming dies l2 -and'i 3. The/mandrel 3B and the forming die ESE-remain atrest in this position for ashort periodof time.

' Theiorming dies 'lzand it are then moved inwardby the cam. members 86 and 81 to the position indicated in dotted lines in Fig. 6, which movement of the dies completes the forming operation of the blank i5- about the mandrel 30. The end portions H andit of the blank l5 will engage the part of the mandrel and be shaped to extend outwardly from thecircular body por-- tion of the article, as indicated in the drawings. On the upward stroke of the ram 43, the cams actuated thereby will return the dies "l2 andlsto their normal retracted position and the slide- 25 and the mandrel 29 to its normal retracted position. The slide 5?} and the die 52 will be movedto their forward position by the spring 64- as the mandrel 29 is retracted.

The for-med article l5 surrounding the mandrel will be carried with the mandrel to a position above enlarged apertures HI and I32- in theplates 22* and 28, respectively, which apertures are aligned with an opening (not shown) in the bolster-plate 21 and through which the article may be ejected. Means to aid in theejection of the. article are provided in the form of a nozzle Hi3, through which air may be forced, the air passing through suitable conduits or apertures ifid in the mandrel communicating with downwardly directed ports H35 in the slide 25.. Should the completed article tend to adhere to. the mandrel, theair being forced through theports 35 will free the article therefrom and in sure itseg ectionthrough the aperture 13L What is claimed is:

1. In an article forming apparatus, a movable mandrelabout which ablank is to be formed, a mcvablefirst forming die spaced from and in alignment with said mandrel and having a recess. forreceiving a portion. of said mandrel, a second forming die having a portion shaped to conform to. a portion of said mandrel andbeing laterally fsposed, adjacent said firstv die, said second forming die being movable in a path transverse.-. ly; -to. the. movement of saidifirst die and normally blockedimitsaforming movement by said firstdie,

means for supporting. said.- blank in. a. predeter mined position between said mandrel and. said dies, said'firstforming die and said mandrel'being shaped and operable to bend said blank into U-shape, means for actuating: said mandrel to first move said. mandrel into the. recess of said first die to partially form said blank about said mandrel into U-shape and. then move said first forming die from the path oi'said second: forming die and align said mandrel and said partially formed strip thereon with said second forming. die, and means for actuating said second forming die to further form: said blank about saidmandrel.

2. In an article forming apparatus, meansfor supporting a blank in a predetermined position, a movable mandrel about which said blank is adapted to be formed disposed on one side of said blank supporting means, a plurality: of forming dies on the other side of said supporting means comprising a movable middle die in alignment with said mandrel and a pair of movable side dies disposed on opposite sides ofand adjacent said middledie; said middledie having a semi-circular recess to: receive a portion of said' mandrel and shaped to bend said blank into U-shape about said mandrel, said middle die also having a normal advanced position adjacent-said blank supporting means; said side dies being transversely movable relative tothe path of movement of said middle die and in paths not in normal alignment with said mandrel, means for advancing said mandrel to a first forming position tocause-the movement ofsaid' blankinto the recess of said middledie to form said blank into U-shape, means for holding said middle die insaidadvanced position-during said formingoperation, means for moving said middle die from the path of said side dies and moving said mandrel with said U-shaped blank thereon into form the blank about said mandrel.

mandrel and said dies, means for feeding said blank to said supporting means, meansfor actuat ing'said mandrel-to move said blank into said recess of said-first forming die to form said blank into U-shape and then movesaid' die to clear. said second forming die and move said mandrel with said U-shaped blank thereon into a p0si-- tion of alignment with said second forming die, means for holding said'first forming die in said normally advanced position during said forming operation'andfor returning said'die to said nor mal advanced position, and means for actuating saidsecond forming die to further form said blank about said mandrel.

. 4. In an article forming apparatus, a base, a

reciprocatablemandrel about which: a blank is to be formed-mounted on said :base;-a. die in align-" ment with said mandrel and having a recess for receiving a portion of said mandrel and shaped to bend said blank into U-shape about said mandrel, said die being longitudinally movable on said base and having a normal position thereon spaced from said mandrel, a transversely movable die mounted on said base laterally disposed adjacent said longitudinally movable die and having its inward movement normally blocked by said longitudinally movable die, means for supporting a blank in a predetermined position between said mandrel and said forming dies, means for moving said mandrel into the recess of said longitudinally movable die to a first forming position to form said blank into U-shape, means for holding said longitudinally movable die stationary during said forming operation, means for moving said mandrel and said U-shaped blank thereon to a second forming position in alignment with said transversely movable die after the first forming operation and for moving said longitudinally movable die from the path of said transversely movable die, means operable while said mandrel remains in said second forming position for actuating said transversely movable die to further form said blank about said mandrel, and means for ejecting said article from said mandrel.

5. An article forming apparatus comprising a movable mandrel about which a blank may be formed, a longitudinally movable forming die spaced from and in alignment with said mandrel and having a recess shaped to receive a conforming portion Of said mandrel therein for bending a blank positioned between said die and said mandrel into U-shaped, transversely movable dies laterally disposed on opposite sides of and adjacent to said longitudinally movable die, said transversely movable dies having portions shaped to conform to portions of said mandrel and having their paths or movement perpendicular to the movement of said movable die and normally blocked by; said longitudinally movable die, means for supporting said blank in a predetermined position between said mandrel and said dies, means for guiding said blank to said blank positioning means, mean for feeding said blank to said positioning means, means for actuating said mandrel to first move said mandrel and said blank into the recess of said first die to form said blank about said mandrel into U-shape and then move said first mentioned die from the path of said transversely movable dies and align said mandrel and said partially formed strip thereon with said transversely movable die, and means for actuating said transversely movable dies to complete the forming of the blank about said mandrel.

6. In an article forming apparatus, a mandrel about which a blank is to be formed, a longitudinally movable die normally spaced from said mandrel and having a semi-circular recess therein for receiving a portion of said mandrel, means yieldingly projecting from the forming surface of said longitudinally movable die for clamping said blank against said mandrel during the forming operation, a transversely movable die disposed laterally adjacent said longitudinally movable die and out of alignment with said mandrel and having its movement normally obstructed by said longitudinally movable die, means for supporting said blank between said mandrel and said dies, means for effecting relative movement between said mandrel and said longitudinally movable die to form said blank into U-shape, means-for efsaid transversely movable die and said mandrel and said longitudinal die to align said transversely movable die with said mandrel and the U-shaped blank thereon and to remove the obstruction to transverse movement of the transversely movable die, and means for advancing said transversely movable die to further form said blank about said mandrel while said mandrel remains stationary.

7. In an article forming apparatus, a mandrel about which a blank is to be formed, a reciprocatable slide for supporting said mandrel, a first forming die having a semi-circular recess formed therein to conform to and to receive a portion of said mandrel, said first forming die being reciprocatable in alignment with said mandrel and having a normal advanced position spaced from said mandrel, a pair of second forming dies having portions thereon shaped to conform to the contour of portions of said mandrel, said second forming dies being mounted on opposite sides of said first forming die and movable in a path transversely of the path of movement of said first forming die, stationary means for supporting and guiding said dies and said mandrel slide, means for supporting said blank in a predetermined position between said dies and said mandrel, a reciprocatable ram, cams mounted on said ram for actuating said mandrel slide and said second forming dies in timed relation whereby said mandrel is advanced into the recess of said first forming die to form said blank into U-shaped and advanced further with the U-shaped blank thereon into alignment with said second forming dies and said second forming dies are advanced to complete the forming of said blank about said mandrel, and resilient means for moving said first forming die to its normal advanced position and holding it there while the blank is formed into U-shape.

8. In an article forming apparatus, a mandrel about which a blank is to be formed, a first forming die having a recess therein for receiving a portion of said mandrel and shaped to bend said blank into U-shape about said mandrel, means for supporting a blank in a predetermined position between said mandrel and said first forming die, means for effecting relative movement between said mandrel and said first forming die to form said blank into U- shape, a second forming die disposed to one side of said first forming die and said mandrel and having a portion thereof shaped to conform to a portion of said mandrel, said second forming die being movable in a path normally out of alignment with said mandrel and perpendicular to the path of relative movement between said mandrel and said first forming die, means for eifecting a relative movement between said second forming die and said mandrel and said first forming die to align said second forming die with said mandrel, and means for moving said second forming die toward the mandrel to further form the blank about said mandrel.

9. An article forming apparatus comprising a first forming member about which a substantially straight blank is to be formed movable in one direction, a second forming member having a recess for receiving a portion of the first forming member and in cooperation therewith to bend the blank around the first forming member into U-shape, a third forming member laterally disposed adjacent said second forming feoting a longitudinal relative movement between member and movable in a direction perpendicular to said one direction and normally out of alignment with said first forming member, means for supporting the blank between the first and the other forming elements, said second and third forming members being relatively movable to permit the alignment of said third forming member with the said partially formed blank and said first forming member whereby the third forming member may be advanced to further form said blank about said first forming member.

10. An article forming apparatus comprising a first forming member about which a straight blank is to be formed movable in one direction, a second forming member having a recess for receiving a portion of the first forming member and in cooperation therewith to form the blank around the first forming member into U- shape, a third forming member laterally disposed adjacent said second forming member and movable in a path perpendicular to said one direction and normally out of alignment with said first forming member, one of said second and third forming members being movable relative to the other parallel to said one direction to permit the alignment of the third forming member with the first where it may be advanced to further form the blank around the first forming member, means for supporting the blank between the first and the other forming members, and means for actuating said forming members in sequence to cause said first and second forming member to form said blank into U- shape and to efiect the proper positioning of the members and the actuation of the third member to further form said blank about said first forming member.

11. An article forming apparatus comprising a first forming member about which a substantially straight blank is to be formed and which is movable in one direction, a movable second forming member having a recess for receiving a portion of said first forming member and for cooperating therewith to bend said blank into U-shape, a third forming member laterally disposed adjacent said second forming member and movable in a path substantially perpendicular to said one direction and adapted to cooperate with said first forming member to further form said blank, means for supporting a blank between said first forming member and said other forming members, said forming members being arranged so that the first forming member may be moved into engagement with the second forming member to bend a blank into U-shape at one position and then advanced to and stopped in another position in the path of movement of said third forming member and causing the movement of said second forming member therewith, whereby said third forming member may be actuated to further form said blank, and means for sequentially actuating said first and third forming members.

12. An article forming apparatus comprising a mandrel about which a substantially straight blank is to be formed and which is movable in a longitudinal path from an inoperative position through a first forming position to a second forming position, a longitudinally movable die normally disposed at said first forming posi tion and engageable with said mandrel for movement therewith from said first forming position to said second forming position, said die having a recess for receiving a portion of said mandrel and for cooperating with said mandrel to bend a blank into U-shape, a transversely movable die disposed laterally of and adjacent said longitudinally movable die in its normal position and adapted to cooperate with said mandrel in its second forming position to further form said blank, means for supporting a blank between said mandrel and said dies, means for advancing said mandrel from said inoperative position to said second forming position to cause said blank to be formed into U-shape about said mandrel at said first forming position and moved to said second forming position, and means operable while said mandrel remains in said second forming position to move said transversely movable die into cooperative engagement with said mandrel to cause the further forming of said blank.

13. In an article forming apparatus, a mandrel about which a substantially straight blank is to beiormed, a longitudinally movable die normally spaced from said mandrel and having a recess therein for receiving a portion of said mandrel and for cooperating therewith to form said blank into U shape, a transversely movable die adapted to cooperate with said mandrel to further form said blank, said transversely movable die being disposed laterally adjacent said longitudinally movable die and movable in a path normally out of alignment with said mandrel and having its movement normally obstruct-ed by said longitudinally movable die, means for supporting said blank between said mandrel and said dies, means for effecting relative longitudinal movement between said mandrel and said longitudinally movable die to form said blank into U shape, means for effecting a relative longitudinal movement between said transversely movable die and the mandrel and the longitudinal die to align said transversely movable die with the mandrel and U shape blank thereon and to remove the obstruction of said longitudinally movable die to transverse movement of the transversely movable die, means for actuating said transversely movable die to further form said blank about said mandrel, and means for holding said mandrel stationary while said transversely movable dies are being actuated.

EDWARD J. BOHABOY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 270,362 Alpress Jan. 9, 1883 1,058,775 McKillop Apr. 15, 1913 1,078,707 Tevander Nov. 18, 1913 1,138,639 Dietrich May 11, 1915 1,163,933 Kurschus Dec. 14, 1915 1,335,908 Mueller Apr. 6, 1920 1,433,879 Fancher Oct. 31, 1922 1,529,746 McDonald Mar. 17, 1925 1,758,237 Paine May 13, 1930 2,121,901 Butty June 28, 1938 2,166,347 Farney July 18, 1939 2,442,908 Sirp June 8, 1948 FOREIGN PATENTS Number Country Date 1,384 Great Britain Jan. 19, 1914 a 28,387 Great Britain Dec. 14, 1903 79,261 Switzerland Dec. 28, 1933 

